<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>HTML嵌套</title>
	</head>
	<body>		
		<!-- good -->
		<p class="first"><em>开心</em>享受前端开发课程！</p>
		<!-- bad -->
		<p class="second"><em>开心享受前端开发课程！</p></em>
	</body>
</html>